Hi all, I trust everyone had an enjoyable festive period. I have a 17" MacBook Pro the model is mid 2010 2.53ghz I run Photoshop, In design and Illustrator frequently and as a result I noticed a slowing down of my system. Decided to upgrade my ram, I bought 2 of the following Corsair 4GB DDR3 1066Mhz Mac Memory SO-DIMM Module CL7 1.5V to take it to its 8gb capacity. I believe that this should all be compatible. After installing what I believe is properly, the system does not launch. I get to the grey screen which shows the apple logo and nothing else. I am able to boot in safe mode, going into the system details shows that I have 8gb ram running no problem. I have verified disk permissions and then repaired them all is ok. After restarting in safe mode and booting in normal mode the same grey screen appears. I have reset the VRAM with no effect, the same error occurs. I have put the old ram in and it works fine in normal mode, no problems. Could someone please shed some light on what is going on and how to fix it. Thanks in advance.